build: parametrize CUDA version for wheels and docker

- Add cu128/cu130 build matrix to release workflow
- Parametrize Dockerfile and docker-compose with CUDA_TAG build arg
- Allow csrc/ and setup.py in docker context via .dockerignore
- Add nvcc/torch CUDA version mismatch preflight warning in setup.py
- Add cuda_toolkit_version() helper in csrc/build.py
- Use at::IntArrayRef explicitly to fix ATen overload ambiguity
- Guard kernels with CUDART_VERSION >= 11020 check
- Remove invalid [tool.pip] section from pyproject.toml

pyproject.toml

@@ -36,9 +36,6 @@ dev = ["pytest==9.0.2", "ruff", "httpx2"]
 [tool.setuptools.packages.find]
 where = ["."]
 
-[tool.pip]
-extra-index-url = "https://download.pytorch.org/whl/cu128"
-
 [tool.setuptools.dynamic]
 version = { attr = "astrai.__version__" }